ABSENCE OF GROWTH IN HYPOPHYSECTOMIZED RATS TREATED WITH THYROID HORMONES

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Abstract
Male rats were hypophysectomized at four weeks of age, rested for four weeks, and then were fed a thyroid digest in their drinking water continuously for up to seventy weeks. The digest treatment supplied the equivalent of 1.25μg L-thyroxine per 100 g rat per day approximately. From the body weight curves and radiographic measurements of the skull and mandibles, it was shown that contrary to some previous reports in the literature there was no statistically significant change in the indices of growth or body mass when compared with controls receiving no thyroid treatment. It is suggested that data previously reported by others, indicating a stimulation of growth in hypophysectomized rats by thyroid hormones, may have been derived from animals having minute but still effective pituitary remnants, and somewhat more stringent morphological criteria of hypophysectomy are proposed.